The adulteration of critical use articles such as surgical gloves and condoms poses considerable health risks. Adulteration as used herein is intended to encompass conditions such as holes formed during the manufacture of an article such as a surgical glove as well as holes formed thereafter for any reason, which holes may provide a path for adulteration of the article by potential dangerous fluids such as body fluids. The term "holes" or "perforations" include not only holes capable of initially passing fluid but also incipient holes, which may initially be too small to pass amounts of fluid but may enlarge over time, or otherwise breach or deteriorate the integrity of the barrier posed by the article. Such holes may even form a danger before reaching a size large enough to pass actual fluid since bacteria may theoretically pass through even smaller openings.
One example of a critical use article is the surgical glove. While problems with surgical gloves will be described shortly, it should be understood that similar problems may be present in any other type of barrier such as condoms, surgical gowns, surgical drapes and the like. The adulteration of gloves used in surgery has long been a problem to the medical doctor or other health care worker. There are two common sources for the creation of holes or perforations in surgical gloves prior and during use. One source is the manufacturer, who, due to lack of quality control or inherent manufacturing problems, may manufacture and sell gloves which already have perforations. In about 1990, the Federal Food and Drug Administration determined by field inspection failure rates of three to sixteen percent in surgical gloves prior to use. The FDA further found that, for patient-examination gloves, average defect rates ranged from 14-18%. In a recent attempt to tighten quality control in surgical gloves, the FDA resorted to its own modification of the well-known and fundamental A.S.T.M. technique for determining defects in gloves--a water fill test.
The second source of holes or perforations in gloves occurs during use. For example, holes or dangerously thin spots may develop in gloves at the time that the surgeon first fits the gloves over his or her hands, or, a glove may be perforated during surgery. Perforations during a surgery can occur because of penetration by sharp objects or because of the breaking down of inherently thin spots in the gloves or areas made thin as a result of putting the glove on the hand or manipulating instruments.
Perforations expose a surgeon to actual or possible contact with patient body fluids because of the resulting adulteration of the gloves. While such adulteration has always been a possible source of infection or the spreading of bacteria to the surgeon or from the surgeon to the patient, the alarming spread of hepatitis and AIDS viruses has created an even more serious problem--the possible spread of an incurable disease from the patient to the surgeon or from the surgeon to the patient. Therefore, the need for accurate and immediate detection of actual or near adulteration in surgical gloves is now at a heightened level because of the potential for the spread of incurable diseases from patient to surgeon or surgeon to patient.
The problems with the AIDS virus is not limited, however, to surgeons or other persons in the operating room such a nurses and anesthesiologists. For example, it is possible that other users of critical use gloves such as dentists or paramedics may be subject to many of the same serious concerns because the dentist or paramedic is also exposed to body fluids during his or her work on a patient. While perhaps less likely, there is also some possibility for the spread of serious diseases from patients to doctors during physical examinations. For purposes of definition, doctors, dentists, nurses and others who may be exposed to disease through gloves or other barriers are defined herein as "health care workers." It is also noted that the problem of communication of a disease between persons due to adulteration of a material acting as a barrier between the persons is not limited to surgical gloves but other articles such as surgical gowns, masks and condoms prevent similar problems.
While the FDA has taken the approach of using the rudimentary water fill method to determine leaks in gloves as manufactured, such simple techniques cannot be used to detect adulteration in gloves during use. There have been some attempts in the prior art to detect the occurrence of perforations in surgical gloves after the gloves are on the doctor's hands, all of which use resistance level detection as the parameter to detect holes. Such level detection concepts have been known for several decades and recently, there have been further attempts at modest improvement on such detection mechanisms, all of which continue to rely on resistance level detection as the principal parameter to be measured.
U.S. Pat. No. 4,321,925 of John Hoborn and Ulrich Krebbs discloses an electronic detector arranged so that the level of electronic conductivity through the gloves and between the patient and surgeon may be sensed at regularly recurring discrete time intervals in order to measure a predetermined level of sensed conductivity and signal an alarm if such predetermined level is met. The detecting circuit of the '925 patent is actually located in one of the shoes of the surgeon and includes one contact located in the insole of the shoe in order to make electrical contact with the surgeon and a second contact exposed to an electrical conducting plate located on the floor of the operating room so that a closed circuit is formed between the operating table, the patient, the doctor, the electrical device located in the shoe and the round conducting element or plate located on the floor of the operating room. The '925 patent teaches that five times per second the disclosed circuit short-circuits the contacts in the insole and in the bottom of the sole of the shoe in order to discharge static electricity from the insole contact which may have accumulated from the doctor. After each short circuit, the circuit is opened between the two contacts and a voltage level sensor is used to detect the level of electrical conductivity which occurs externally between the contacts.
The impedance of the latex or rubber that comprises surgical gloves is high. If there is a perforation in the operating gloves of the surgeon, which fills with body or other electrically conducting fluid, the impedance is thereby reduced and a greater conductivity is provided by the gloves. The '925 patent teaches that the occurrence of a perforation in the operating gloves may result in a relatively high electric conductivity between the surgeon and patient, thus allowing the sensing device to sound an alarm upon the occurrence of a predetermined level of sensed conductivity. Setting of the appropriate level of conductivity is strictly a matter of design and thus it is believed that one drawback to the device of the '925 patent is that the level of conductivity required to trigger the alarm may differ from glove to glove, depending upon the nature of the material, the thickness of the material and any other factors which may impact upon the general conductivity of the series circuit, which includes not only the doctor and patient, but also the doctor's shoes, a round plate located on the operating floor, and the operating table itself. Therefore, the '925 patent may work fairly well for certain types of gloves whose characteristics conform to the particular resistance level chosen for the resistance level sensor, but the '925 patent may not work well with many other types of gloves. In order to function properly, the resistance level sensor of the '925 patent would have to be adjusted to some pre-determined level depending upon the type of glove used and could even further require additional level adjustments during the period in which the glove is used.
Perhaps more importantly, the tendency of latex to absorb fluid during use is a factor not solved by the '925 Hoborn patent and other similar resistance level detection devices. Most natural rubber latex gloves absorb considerable quantities of water with time, referred to as hydration. This hydration effect causes the conductivity of the glove to increase markedly, thus decreasing its resistance. Eventually, the electrical resistance of the gloves becomes as low as a glove with a hole in it. Thus, for many types of surgeons, gloves, devices like that shown in the '925 patent will eventually give a hole alarm when there is no perforation. Therefore, the fact that the absolute conductivity of a glove varies with the hydration of the glove material detracts from the effectiveness of the sensor of the '925 device. There are other patents which disclose level detection type devices which are believed to have disadvantages similar to the '925 patent, such as U.S. Pat. Nos. 4,956,635 of Langdon and 5,036,309 of Dennison.
Other prior art devices include several devices that utilize a basin of conductive fluid in which the surgeon places his or her gloved hands for the purposes of determining whether or not the gloves have become adulterated. See U.S. Pat. Nos. 2,981,886 of Beck; 4,810,971 of Marable; 4,909,069 of Albin; and 4,956,635 of Langdon. If the conductive fluid in the basin enters a gloved hand or comes in contact with body fluid already in the adulterated glove, increased conductivity is detected. Other devices and relevant prior art will be discussed in appropriate submitted Information Disclosure Statements.
One solution to this problem is found in U.S. Pat. Nos. 5,144,425 of Robert E. Williams, William H. Marshall, Robert B. Stout and John J. McCourt, Jr., entitled "Method and Apparatus for Detecting Actual or Likely Adulteration of Critical Use Gloves." The '425 patent of Williams, et al. was issued on May 19, 1992 and discloses apparatus and method for detecting adulteration or a condition of near-adulteration of a glove in critical use application such as surgery where the gloves are worn by the surgeon and are exposed to the body fluids of a patient. The apparatus and method include a detection not only of a particular level of conductivity but also detection of a sudden change in conductivity which may be caused by a sudden change in condition of the glove, such as the opening of a hole in the glove or a sudden thinning of a glove. In this manner, the apparatus and method detect not only the actual condition of the glove but also a condition of change of the glove.
Following the same concept, but improving thereon, is U.S. patent application Ser. No. 07/846,539 the parent application to this application, entitled "Enhanced Monitor Device for Surgical Gloves and Other Barriers" filed on Mar. 4, 1992. In this patent application, an even newer and more improved monitoring device for detection of holes in gloves and other barriers is disclosed. The monitoring device can reliably monitor the integrity of gloves for an extended period and is suitable for use with a number of different glove-types from different glove manufacturers. The monitoring device is a programmable, configurable and self-adapting device which continuously measures the resistance, the rate of change or first derivative of resistance and the rate of the rate of change or second derivative of resistance across the gloves worn by the health care worker and a circuit comprised of the patient, health care worker and the gloves. The device distinguishes between sudden or rapid, transient change in resistance caused by a hole or puncture in the glove and a more gradual and/or continuous change in resistance caused by normal glove hydration. With the use of either the monitor of U.S. patent application Ser. No. 5,144,425 or the monitor of U.S. patent application Ser. No. 07/846,539, it is necessary that a convenient but highly reliable electrical connection be made between the doctor and patient so that the necessary electrical circuit can be completed upon the occurrence of a hole or other adulteration or aberration in the glove or other barrier. One such electrical connection is described with respect to the Hoborn '925 patent. However, such device requires the wearing of special shoes and the equipping of the operating room with a special conducting plate, which creates not only additional capital expense but also certainly additional maintenance expense.
It is desirable that an efficient, highly reliable but convenient electrical connection be made between the health care worker such as a doctor or dentist and the patient. Factors which cause this problem to be difficult to solve include the fact that the doctor, such as a surgeon during an operation, needs to be mobile. Therefore, the surgeon cannot be fixed to an operating table by some semi-permanent electrical connection which would prevent the surgeon from moving about the operating table or moving to another location to check an instrument, review x-rays or the like. Similarly, other health care workers such as dentists need to be able to move freely around a patient and within an office in order to organize equipment and be positioned properly for working on the patient.